ChristopherZielinski avatar image
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ChristopherZielinski asked ChristopherZielinski published

UWP access to COM3 (Serial Port) on Panasonic Tablet (FZ-F1) -

SerialDevice.FromIdAsync( ) is always returning null due to "Access to the device was blocked by the system : \\?\USB#VID_1546&PIC_01A8#5&46E708A&0&10#{86e0d1e0-8089-11d0-9ce4-08003e301f73}"

I did request access to the device in the UWP application manifest...


But, _device is always getting assigned null, in the following code...

 public async Task AttachedToGps()
     const uint baudRate = 9600;
     const ushort dataBits = 8;
     const SerialParity parity = SerialParity.None;
     ushort vid = 0x1546;
     ushort pid = 0x01A8;
     var selector = SerialDevice.GetDeviceSelectorFromUsbVidPid(vid, pid);
     var devices = await DeviceInformation.FindAllAsync(selector);
     if (devices.Any())
         var deviceInfo = devices.First();
         _device = await SerialDevice.FromIdAsync(deviceInfo.Id);
         _device.BaudRate = baudRate;
         _device.DataBits = dataBits;
         _device.Parity = parity;
         _device.ReadTimeout = TimeSpan.FromMilliseconds(500);
         _device.WriteTimeout = TimeSpan.FromMilliseconds(500);
         _deviceChannel = new NmeaParser.SerialPortDevice(_device);
     return _deviceChannel;

What more do I need to do, to get access to this serial communications device? This source code did work on an older version of the device (and Windows 10 Pro O/S).

Many thanks to anyone that can help!

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Please check if the device's pid and vid is correct and check the device drive is running, and make sure the device was not been disabled.

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hi ChristopherZielinski, do you solve this issue, and do you have any updates for this case

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Hacked a workaround (replaced the u-blox serial COM port driver with Microsoft's; captured longitude; latitude; velocity; course; and, satellite count via a .Net Framework Windows service that binary serialized the data to disk for the UWP program to deserialize at fairly frequent intervals).

The hardware Id for the u-blox Virtual COM Port (by default on COM5) is...

n.b.: The u-blox GNSS Location Sensor has a PID, VID hardware Id and it is...

Any help would be welcomed and appreciated.

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Any updates about this issue? Please feel free to contact us if you have any other questions.

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With an older Panasonic FZ-G1 Toughpad tablet, I was able to acquire GPS information from the serial COM3 port after adding the COM port permission in the application's manifest and making the following Windows Registry change...

 [reg add HLKM\SYSTEM\ControlSet001\Control\DeviceOverrides\ACPI#PNP0501\LocationPaths\* /v removable /t REG_DWORD /d 1]

However, I was recently provided with the most recent Panasonic FZ-G1 Toughpad tablet and the GPS chipset(s) were completely updated.

I reached out to both Panasonic and u-blox (the GPS chipset maker), but neither were able to assist. u-blox said that they could not see how they could help.

The u-blox GPS serial COM port driver seems to be a USB-to-COM driver. Both .Net Framework (v4.7.2) and UWP are unable to access the serial COM port when the u-blox drivers are correctly installed.

I have not had time to see if I can acquire the GPS NMEA data directly from the USB driver. The USB approach seems more complicated.

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1 Answer

RoyLi-MSFT avatar image
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RoyLi-MSFT answered ChristopherZielinski published


Welcome to Microsoft Q&A!

It seems that Windows.Devices.SerialCommunication.SerialDevice class can't get SerialDevice instance of a virtual COM port. It will return null like the result you got.
You could try to use System.IO.Ports.SerialPort class instead.
Please refer to this Blog: How to access virtual COM port from UWP app for more information.

Thank you.

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Thank you so very much!

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Note: The provided solution only works if the Panasonic Toughpad u-blox USB-to-COM port driver is replaced by the Microsoft USB Serial Device driver. This modification will disable the Windows Location service, as the complete u-blox driver set is no longer able to participate.

.NET Framework and UWP are unable to open the u-blox serial driver by name ("COM3").

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